Investigating Overcharge-Induced Thermal Runway of Lithium Batteries Using a Coupled Electrochemical-Thermal-Venting Model

Abstract

The overcharge-induced thermal runaway process of lithium-ion battery is extremely difficult to model due to the complex materials and phase changes. In this work, a coupled electrochemical-thermal-venting model is established to accurately simulate the highly interactive electrochemical-thermal, gas generation and gas venting behaviors, which is the first attempt to connect the electrochemical-thermal characteristics with gas generation mechanisms. In this model, the pseudo-two-dimensions model and tree-dimensions model are coupled to simulate the highly interactive electrochemical-thermal behavior. The gas generation model is built based on kinetic analysis, which can exactly reveal the inner gas change of electrolyte oxidation, electrolyte reduction, and solid electrolyte interphase (SEI) decomposition. The modeling analysis comprehensively quantify the detailed heat generation and force generation of each source. The experimental results demonstrate that the electrolyte reduction on the anode contribute most to the gas and heat generation. Meanwhile, the visualization of thermal distribution and expansion distribution during overcharge process sheds new light on the safety design of lithium batteries. Moreover, the proposed model can be used to monitor the gas changes before venting and predict upcoming thermal runaway events.

Keywords: Lithium-ion battery safety, Overcharge, Gas generation model, Internal pressure, Gas venting